How can I get the user data in serializer `create()` method?

Question

How can I get the user data in serializer create() method?

I tried to get the user data use self.request, but failed:

class OrderCreateSerializer(ModelSerializer):
    class Meta:
        model = Order
        fields = (
            "product_describe",
            "billing_type",  
            "buytime",  
            "count",  
            "paytype",  
        )
    def create(self, validated_data):

        print(self.request.user.username)

        validated_data["order_num"] = generateOrderNum()

        return Order.objects.save()

'OrderCreateSerializer' object has no attribute 'request'